CHARACTERISTICS OF MICROSTRUCTURES OF NI-AU AND PD-AU ALLOY-FILMS PREPARED BY AN EVAPORATION METHOD

The influence of film preparation process on phase separation or inter diffusion has been studied for Ni-Au alloy films and Au/Pd bilayer fil ms. Microstructures of the films were observed by a transmission elect ron microscope. The microstructures of the Ni-Au alloy films which wer e annealed after removal from substrates were consistent with those of bulk specimens, while the Ni-Au alloy film which was epitaxially grow n on a substrate exhibited a different microstructure from that expect ed from the equilibrium state. Moire patterns were always seen for all the as-deposited Au/Pd epitaxial bilayer films. and they disappeared gradually with annealing, showing that Au/Pd bilayer films were transf ormed to be a homogeneous single phase. The analysis of the changes in moire fringe spacing during annealing showed that the diffusion took place more rapidly in the Au(001)/Pd(001) films than in the Au(111)/Pd (111) films. This is not explained by a concept that diffusion takes p lace equivalently in any orientations. It is shown that the characteri stics of phase separation or interdiffusion in alloy films prepared by evaporation are not always the same as those of bulk alloys.